/*
 * Created on Sep 27, 2007
 *
 * Copyright (c) 2007, Jonathan Fuerth
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Jonathan Fuerth nor the names of other
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package net.bluecow.robot.resource;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

/**
 * The CompoundResourceLoader composes two other resource loaders, treating
 * one as the primary and the other as a backup.  If a certain resource
 * exists only in the primary resource loader or in both the primary and
 * backup loaders, this resource loader will deal with the resource in the
 * primary loader.  Otherwise, if a resource exists only in the backup
 * resource loader and not in the primary, this resource loader will return
 * that resource.  Finally, if a resource exists in neither loader, this
 * resource loader will behave as if the resource does not exist.
 *
 * @author fuerth
 * @version $Id:$
 */
public class CompoundResourceLoader implements ResourceLoader {

    private final ResourceLoader primary;
    private final ResourceLoader backup;
    
    public CompoundResourceLoader(ResourceLoader primary, ResourceLoader backup) {
        this.primary = primary;
        this.backup = backup;
    }

    public InputStream getResourceAsStream(String resourceName) throws IOException {
        try {
            return primary.getResourceAsStream(resourceName);
        } catch (FileNotFoundException ex) {
            return backup.getResourceAsStream(resourceName);
        }
    }

    public byte[] getResourceBytes(String resourceName) throws IOException {
        try {
            return primary.getResourceBytes(resourceName);
        } catch (FileNotFoundException ex) {
            return backup.getResourceBytes(resourceName);
        }
    }
}
